Abstract: An iron-type golf club head that includes a rear wall having a variable thickness region. The variable thickness region includes a plurality of recesses formed in an interior surface of the rear wall. A thickness of the rear wall, defined by the recesses, is less than the thickness of the rear wall between the recesses. A body of the golf club head includes a face opening, a toe port, and an internal-weight cavity. The golf club head also includes a strike plate, attached to the body so that the strike plate covers the face opening, and an internal weight, seated in the internal-weight cavity. An internal cavity of the golf club head is configured to receive the filler material through the toe port. A ratio of a minimum rear wall thickness to a minimum face thickness is between 0.15 to 0.65.

Abstract: Disclosed herein is an iron-type golf club head that comprises a body, made of a first material having a first density. The iron-type golf club head also comprises a weight located within the internal cavity. The iron-type golf club head further comprises a filler material that has a density no less than 0.21 g/cc. The filler material has a mass no less than 2.5 grams and no more than 8 grams. The internal cavity has an internal cavity volume ranging between 5 cc to 20 cc. A ratio of the internal cavity volume to external club head volume ranges between 0.14 and 0.385. The internal cavity has a minimum front-to-back depth above a midplane of the golf club head of no less than 1.4 mm and a maximum front-to-back depth of the internal cavity above the midplane of the golf club head is no more than 13 mm.

Abstract: An iron-type golf club head where a ratio of a maximum toe height of the iron-type golf club head to a blade length of the iron-type golf club head is greater than zero and at most 0.62. A maximum thickness of the front portion, along the strike face, corresponds with a location toeward of a geometric center of the strike face. The thickness of the front portion, at the geometric center of the strike face, is less than the maximum thickness of the front portion. A coefficient of restitution (COR) of the iron-type golf club head is at least 0.818 and at most 0.830. An entirety of the sole is rounded along a plane parallel to the strike face, and a radius of curvature of the sole, along the plane parallel to the strike face, is no more than between, and inclusive of, 100 mm and 275 mm.

Abstract: Disclosed herein is an iron-type golf club head that comprises a body, made of a first material having a first density. The iron-type golf club head also comprises a weight located within the internal cavity. The iron-type golf club head further comprises a filler material that has a density no less than 0.21 g/cc. The filler material has a mass no less than 2.5 grams and no more than 8 grams. The internal cavity has an internal cavity volume ranging between 5 cc to 20 cc. A ratio of the internal cavity volume to external club head volume ranges between 0.14 and 0.385. The internal cavity has a minimum front-to-back depth above a midplane of the golf club head of no less than 1.4 mm and a maximum front-to-back depth of the internal cavity above the midplane of the golf club head is no more than 13 mm.

Abstract: Disclosed herein is an iron-type golf club head that comprises a body, made of a first material having a first density. The iron-type golf club head also comprises a weight located within the internal cavity. The iron-type golf club head further comprises a filler material that has a density no less than 0.21 g/cc. The filler material has a mass no less than 2.5 grams and no more than 8 grams. The internal cavity has an internal cavity volume ranging between 5 cc to 20 cc. A ratio of the internal cavity volume to external club head volume ranges between 0.14 and 0.385. The internal cavity has a minimum front-to-back depth above a midplane of the golf club head of no less than 1.4 mm and a maximum front-to-back depth of the internal cavity above the midplane of the golf club head is no more than 13 mm.